netdev - [BUG dsa] lack of barriers in netdev_uses

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <CANn89i+UsejDXBJv-SqPJTCb-jO7p_+28zVLOOxvHoyV2MKwCQ@mail.gmail.com>
Date: Thu, 29 Jan 2026 14:16:56 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: Andrew Lunn <andrew@...n.ch>, Vladimir Oltean <olteanv@...il.com>
Cc: netdev <netdev@...r.kernel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Jakub Kicinski <kuba@...nel.org>
Subject: [BUG dsa] lack of barriers in netdev_uses_dsa()

Hi dsa experts

It seems netdev_uses_dsa() does not have any barrier.

A compiler could read dev->dsa_ptr and get a NULL the second time.

include/net/dsa.h:1336:static inline bool netdev_uses_dsa(const struct
net_device *dev)
include/net/dsa.h-1337-{
include/net/dsa.h-1338-#if IS_ENABLED(CONFIG_NET_DSA)
include/net/dsa.h-1339- return dev->dsa_ptr && dev->dsa_ptr->rcv;
include/net/dsa.h-1340-#endif
include/net/dsa.h-1341- return false;
include/net/dsa.h-1342-}

I was looking at this because I wanted to inline eth_type_trans().

Note the wmb() in dsa_conduit_teardown(), which is not good enough.

Any suggestions?

Ideally, it would be nice if netdev_uses_dsa() could test a single bit
in "struct net_device",
without a dereference of dsa_ptr.

Thanks.